1. Field
Example embodiments relate to photomasks, methods of exposing a substrate to light, methods of forming a pattern, and methods of manufacturing a semiconductor device.
2. Description of the Related Art
A single patterning method includes a method of forming a pattern of an integrated circuit (IC) by performing an exposure process once. In the single patterning method, a pattern having a uniform line width may be easily formed because the exposure process may be performed using the same exposure mask under the same conditions. An apparatus used for the exposure process, however, may have a limited resolution so that a line width of a pattern may not be sufficiently reduced in the single patterning method.
A double patterning method and a multi-patterning method may be used for overcoming the problems of the single patterning method. The double patterning method may include a method of forming a fine pattern of an integrated circuit (IC) by performing an exposure process twice. A minimum pitch of the pattern may be reduced by half in the double patterning method when compared to the single patterning method. Thus, the double patterning method may be effectively applied to manufacturing a semiconductor device having a critical dimension (CD) less than about 50 nm.
The multi-patterning method may include performing an exposure process more than two times. The multi-patterning method may also reduce a minimum pitch of the pattern when compared to the single pattern method.
In the double patterning method and the multi-patterning method, an each exposure process may be performed using different masks. When the masks are replaced with each other, however, misalignments between the masks may occur.